1. Field of the Invention
This invention relates to means for coating connecting portions or terminal portions of lead wires such as telephone cables and electrical wires, connecting portions in wire harnesses for an automobile, connecting portions between control consoles for electric equipments and lead wires, connecting portions between cables in various plants, connecting portions of optical fiber cables, connecting portions of pipes, or the like by use of a single liquid type moisture curing resin.
2. Description of the Prior Art
For instance, as the wire harnesses used in an automobile, there are a main harness, sound harness, engine harness, rear harness, door harness, instrument harness and so on. These wire harnesses are constituted by connecting various lead wires.
The connecting portions (engaging parts) in such a connection wire harness to be protected have been coated with various coating materials including an insulating vinyl tape, thermoplastic resins, heat-shrinkable tube and sticky gel material, in order to prevent bad influences of the infiltration of water or seawater which possibly corrode the wires, thereby causing connection failure or breaking of connection. The coating on the connecting portions has been fulfilled in the following manner.
1 The insulating vinyl tape has been used as a coating material and wound around the connecting portions to be connected to each other. PA1 2 the resin is molded by extrusion and solidified along with the connecting portions to be connected, PA1 3 the resin is formed in a sheet and subjected to thermocompression bonding with the connecting portions to be connected, and PA1 4 molten thermoplastic resin is poured into a container in which the connecting portions to be connected are inserted, thereby to seal the connecting portions within the container. PA1 5 In a case that the heat-shrinkable tube is used as a coating material, upon insertion of the connecting portions to be connected in the heat-shrinkable tube, the tube is heated at a prescribed temperature to be shrunk. PA1 6 In a case that the sticky gel is used as a coating material, the connecting portions are inserted in a container filled with the sticky gel. PA1 However, the above methods 1.about.6 for connecting the connecting portions entailed the disadvantages as follows.
In a case that the thermoplastic resin is used as a coating material,
When the vinyl tape is wound around the connecting portions to be connected to each other in the method 1 noted above, the tape must be wound around the connecting portions while being applied with strong tension to the tape; otherwise air bubbles or air layers are confined in the winding of the tape, thereby making the sealing property worse. Besides, when winding of the tape is done by hand, the work of winding the tape requires labor and suffers productive and working inefficiencies.
The method 2 in which the thermoplastic resin is used as a coating material necessitates an extrusion molding machine or other equipments results in a large overall size of the coating system. Moreover, the processing for practicing this method cannot be proceeded with until the molten thermoplastic resin is cooled to room temperature. According to the method 3, the sheet-like thermoplastic resin cannot be closely stuck on nor attain complete sealing of the connecting portions, resulting in the infiltration of water or the like into the sealing. In the method 4, since the molten resin is poured into the container and solidified with the connecting portions inserted in the container, there is a case that the connecting portions get out of place or snap in the container.
According to the method 5, the work of inserting the connecting portions into the tube becomes onerous, and the connecting portions cannot be steadily held in the tube. Furthermore, when the connecting portions are already spliced to each other, this method in which the connecting portions must be inserted into the tube is not adaptable, consequently to make the coating impossible by this method.
According to the method 6 using a gelatinous sealing compound which is weak in adhesive strength, the connecting portions retained by the solidified gelatinous sealing compound are easily bared due to strong tension exerted thereon. Thus, the gelatinous sealing compound has little effect of sealing the connecting portions.
The coating materials as noted above by and large do not possess the effect of complete waterproof. Thus, in a case of a car, for example, the wire harness has been arranged so as to hold the connecting portions in position inside the car in order to prevent the connecting portions from causing connection failure or being broken due to the infiltration of water or seawater into the connecting portions. However, this method of wiring requires a troublesome chore, increases the weight and size of the wire harness and calls for large space for accemmodating the large-sized wire harness. Thus, the coating materials produced by the aforementioned method inevitably turn out to be expensive.
There has been proposed a method for sealing connecting portions of conductive wires by use of a photocurable resin, in U.S. Pat. No. 5,099,088 to Usami et al. The photocurable resin used in this prior art is contained in a light-shielding container. However, this conventional method calls for onerous work of exposing the resin to light or ultraviolet rays, when coating the connecting portions with the resin.